Prepare a double sink setup. Rinse chitterlings thoroughly under cool water, inspecting each piece and removing any inner membranes to ensure they are clean.
Place cleaned chitterlings in a large pot, cover with water, and boil for 20 minutes. Drain and rinse to remove final impurities.
Fill a large 5-gallon pot with 1.5 to 2 gallons of water. Add onion, green pepper, seasoned salt, garlic powder, black pepper, red pepper flakes, and apple cider vinegar. Bring to a rapid boil.
Reduce heat to medium. Add the chitterlings one by one, stirring gently to distribute seasoning.
Cover and simmer for 3 hours, or until meat is tender, white, and fluffy. Check liquid levels occasionally and add water if needed.
Taste and adjust seasoning if necessary. Serve hot with hot sauce.
Notes
Store leftovers in an airtight container with cooking liquid for up to 4 days. Reheat gently on the stove over low heat.